1
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Novak JK, Gardner JG. Current models in bacterial hemicellulase-encoding gene regulation. Appl Microbiol Biotechnol 2024; 108:39. [PMID: 38175245 PMCID: PMC10766802 DOI: 10.1007/s00253-023-12977-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 01/05/2024]
Abstract
The discovery and characterization of bacterial carbohydrate-active enzymes is a fundamental component of biotechnology innovation, particularly for renewable fuels and chemicals; however, these studies have increasingly transitioned to exploring the complex regulation required for recalcitrant polysaccharide utilization. This pivot is largely due to the current need to engineer and optimize enzymes for maximal degradation in industrial or biomedical applications. Given the structural simplicity of a single cellulose polymer, and the relatively few enzyme classes required for complete bioconversion, the regulation of cellulases in bacteria has been thoroughly discussed in the literature. However, the diversity of hemicelluloses found in plant biomass and the multitude of carbohydrate-active enzymes required for their deconstruction has resulted in a less comprehensive understanding of bacterial hemicellulase-encoding gene regulation. Here we review the mechanisms of this process and common themes found in the transcriptomic response during plant biomass utilization. By comparing regulatory systems from both Gram-negative and Gram-positive bacteria, as well as drawing parallels to cellulase regulation, our goals are to highlight the shared and distinct features of bacterial hemicellulase-encoding gene regulation and provide a set of guiding questions to improve our understanding of bacterial lignocellulose utilization. KEY POINTS: • Canonical regulatory mechanisms for bacterial hemicellulase-encoding gene expression include hybrid two-component systems (HTCS), extracytoplasmic function (ECF)-σ/anti-σ systems, and carbon catabolite repression (CCR). • Current transcriptomic approaches are increasingly being used to identify hemicellulase-encoding gene regulatory patterns coupled with computational predictions for transcriptional regulators. • Future work should emphasize genetic approaches to improve systems biology tools available for model bacterial systems and emerging microbes with biotechnology potential. Specifically, optimization of Gram-positive systems will require integration of degradative and fermentative capabilities, while optimization of Gram-negative systems will require bolstering the potency of lignocellulolytic capabilities.
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Affiliation(s)
- Jessica K Novak
- Department of Biological Sciences, University of Maryland - Baltimore County, Baltimore, MD, USA
| | - Jeffrey G Gardner
- Department of Biological Sciences, University of Maryland - Baltimore County, Baltimore, MD, USA.
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2
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Yang Z, Li B, Bu R, Wang Z, Xin Z, Li Z, Zhang L, Wang W. A highly efficient method for genomic deletion across diverse lengths in thermophilic Parageobacillus thermoglucosidasius. Synth Syst Biotechnol 2024; 9:658-666. [PMID: 38817825 PMCID: PMC11137367 DOI: 10.1016/j.synbio.2024.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/07/2024] [Accepted: 05/16/2024] [Indexed: 06/01/2024] Open
Abstract
Parageobacillus thermoglucosidasius is emerging as a highly promising thermophilic organism for metabolic engineering. The utilization of CRISPR-Cas technologies has facilitated programmable genetic manipulation in P. thermoglucosidasius. However, the absence of thermostable NHEJ enzymes limited the capability of the endogenous type I CRISPR-Cas system to generate a variety of extensive genomic deletions. Here, two thermophilic NHEJ enzymes were identified and combined with the endogenous type I CRISPR-Cas system to develop a genetic manipulation tool that can achieve long-range genomic deletion across various lengths. By optimizing this tool-through adjusting the expression level of NHEJ enzymes and leveraging our discovery of a negative correlation between GC content of the guide RNA (gRNA) and deletion efficacy-we streamlined a comprehensive gRNA selection manual for whole-genome editing, achieving a 100 % success rate in randomly selecting gRNAs. Notably, using just one gRNA, we achieved genomic deletions spanning diverse length, exceeding 200 kilobases. This tool will facilitate the genomic manipulation of P. thermoglucosidasius for both fundamental research and applied engineering studies, further unlocking its potential as a thermophilic cell factory.
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Affiliation(s)
- Zhiheng Yang
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
| | - Bixiao Li
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science, Ministry of Education, Frontiers Science Center for High Energy Material, Advanced Research Institute of Multidisciplinary Science, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Ruihong Bu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhengduo Wang
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
| | - Zhenguo Xin
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zilong Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Lixin Zhang
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
| | - Weishan Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
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3
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Wang S, Zeng X, Jiang Y, Wang W, Bai L, Lu Y, Zhang L, Tan GY. Unleashing the potential: type I CRISPR-Cas systems in actinomycetes for genome editing. Nat Prod Rep 2024; 41:1441-1455. [PMID: 38888887 DOI: 10.1039/d4np00010b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Covering: up to the end of 2023Type I CRISPR-Cas systems are widely distributed, found in over 40% of bacteria and 80% of archaea. Among genome-sequenced actinomycetes (particularly Streptomyces spp.), 45.54% possess type I CRISPR-Cas systems. In comparison to widely used CRISPR systems like Cas9 or Cas12a, these endogenous CRISPR-Cas systems have significant advantages, including better compatibility, wide distribution, and ease of operation (since no exogenous Cas gene delivery is needed). Furthermore, type I CRISPR-Cas systems can simultaneously edit and regulate genes by adjusting the crRNA spacer length. Meanwhile, most actinomycetes are recalcitrant to genetic manipulation, hindering the discovery and engineering of natural products (NPs). The endogenous type I CRISPR-Cas systems in actinomycetes may offer a promising alternative to overcome these barriers. This review summarizes the challenges and recent advances in CRISPR-based genome engineering technologies for actinomycetes. It also presents and discusses how to establish and develop genome editing tools based on type I CRISPR-Cas systems in actinomycetes, with the aim of their future application in gene editing and the discovery of NPs in actinomycetes.
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Affiliation(s)
- Shuliu Wang
- State Key Laboratory of Bioreactor Engineering (SKLBE), School of Biotechnology, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Xiaoqian Zeng
- State Key Laboratory of Bioreactor Engineering (SKLBE), School of Biotechnology, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Yue Jiang
- State Key Laboratory of Bioreactor Engineering (SKLBE), School of Biotechnology, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Weishan Wang
- State Key Laboratory of Microbial Resources and CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing 100101, China
| | - Linquan Bai
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yinhua Lu
- College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Lixin Zhang
- State Key Laboratory of Bioreactor Engineering (SKLBE), School of Biotechnology, East China University of Science and Technology (ECUST), Shanghai 200237, China.
| | - Gao-Yi Tan
- State Key Laboratory of Bioreactor Engineering (SKLBE), School of Biotechnology, East China University of Science and Technology (ECUST), Shanghai 200237, China.
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Sitara A, Hocq R, Horvath J, Pflügl S. Industrial biotechnology goes thermophilic: Thermoanaerobes as promising hosts in the circular carbon economy. BIORESOURCE TECHNOLOGY 2024; 408:131164. [PMID: 39069138 DOI: 10.1016/j.biortech.2024.131164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Revised: 07/19/2024] [Accepted: 07/24/2024] [Indexed: 07/30/2024]
Abstract
Transitioning away from fossil feedstocks is imperative to mitigate climate change, and necessitates the utilization of renewable, alternative carbon and energy sources to foster a circular carbon economy. In this context, lignocellulosic biomass and one-carbon compounds emerge as promising feedstocks that could be renewably upgraded by thermophilic anaerobes (thermoanaerobes) via gas fermentation or consolidated bioprocessing to value-added products. In this review, the potential of thermoanaerobes for cost-efficient, effective and sustainable bioproduction is discussed. Metabolic and bioprocess engineering approaches are reviewed to draw a comprehensive picture of current developments and future perspectives for the conversion of renewable feedstocks to chemicals and fuels of interest. Selected bioprocessing scenarios are outlined, offering practical insights into the applicability of thermoanaerobes at a large scale. Collectively, the potential advantages of thermoanaerobes regarding process economics could facilitate an easier transition towards sustainable bioprocesses with renewable feedstocks.
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Affiliation(s)
- Angeliki Sitara
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
| | - Rémi Hocq
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria; Christian Doppler Laboratory for Optimized Expression of Carbohydrate-active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria; CIRCE Biotechnologie GmbH, Kerpengasse 125, 1210 Vienna, Austria
| | - Josef Horvath
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria; Christian Doppler Laboratory for Optimized Expression of Carbohydrate-active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
| | - Stefan Pflügl
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria; Christian Doppler Laboratory for Optimized Expression of Carbohydrate-active Enzymes, Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria.
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Ponsetto P, Sasal EM, Mazzoli R, Valetti F, Gilardi G. The potential of native and engineered Clostridia for biomass biorefining. Front Bioeng Biotechnol 2024; 12:1423935. [PMID: 39219620 PMCID: PMC11365079 DOI: 10.3389/fbioe.2024.1423935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 08/06/2024] [Indexed: 09/04/2024] Open
Abstract
Since their first industrial application in the acetone-butanol-ethanol (ABE) fermentation in the early 1900s, Clostridia have found large application in biomass biorefining. Overall, their fermentation products include organic acids (e.g., acetate, butyrate, lactate), short chain alcohols (e.g., ethanol, n-butanol, isobutanol), diols (e.g., 1,2-propanediol, 1,3-propanediol) and H2 which have several applications such as fuels, building block chemicals, solvents, food and cosmetic additives. Advantageously, several clostridial strains are able to use cheap feedstocks such as lignocellulosic biomass, food waste, glycerol or C1-gases (CO2, CO) which confer them additional potential as key players for the development of processes less dependent from fossil fuels and with reduced greenhouse gas emissions. The present review aims to provide a survey of research progress aimed at developing Clostridium-mediated biomass fermentation processes, especially as regards strain improvement by metabolic engineering.
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Affiliation(s)
| | | | - Roberto Mazzoli
- Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy
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Mazzoli R, Pescarolo S, Gilli G, Gilardi G, Valetti F. Hydrogen production pathways in Clostridia and their improvement by metabolic engineering. Biotechnol Adv 2024; 73:108379. [PMID: 38754796 DOI: 10.1016/j.biotechadv.2024.108379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 05/13/2024] [Accepted: 05/13/2024] [Indexed: 05/18/2024]
Abstract
Biological production of hydrogen has a tremendous potential as an environmentally sustainable technology to generate a clean fuel. Among the different available methods to produce biohydrogen, dark fermentation features the highest productivity and can be used as a means to dispose of organic waste biomass. Within this approach, Clostridia have the highest theoretical H2 production yield. Nonetheless, most strains show actual yields far lower than the theoretical maximum: improving their efficiency becomes necessary for achieving cost-effective fermentation processes. This review aims at providing a survey of the metabolic network involved in H2 generation in Clostridia and strategies used to improve it through metabolic engineering. Together with current achievements, a number of future perspectives to implement these results will be illustrated.
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Affiliation(s)
- Roberto Mazzoli
- Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123 Torino, Italy.
| | - Simone Pescarolo
- Biology applied to the environment, Laboratories of microbiology and ecotoxicology, Ecobioqual, Environment Park. Via Livorno 60, 10144 Torino, Italy
| | - Giorgio Gilli
- Department of Sciences of Public Health and Pediatrics, School of Medicine, University of Torino, Via Santena 5 bis, 10126 Torino, Italy
| | - Gianfranco Gilardi
- Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123 Torino, Italy
| | - Francesca Valetti
- Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123 Torino, Italy.
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7
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Bales MK, Vergara MM, Eckert CA. Application of functional genomics for domestication of novel non-model microbes. J Ind Microbiol Biotechnol 2024; 51:kuae022. [PMID: 38925657 PMCID: PMC11247347 DOI: 10.1093/jimb/kuae022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 06/25/2024] [Indexed: 06/28/2024]
Abstract
With the expansion of domesticated microbes producing biomaterials and chemicals to support a growing circular bioeconomy, the variety of waste and sustainable substrates that can support microbial growth and production will also continue to expand. The diversity of these microbes also requires a range of compatible genetic tools to engineer improved robustness and economic viability. As we still do not fully understand the function of many genes in even highly studied model microbes, engineering improved microbial performance requires introducing genome-scale genetic modifications followed by screening or selecting mutants that enhance growth under prohibitive conditions encountered during production. These approaches include adaptive laboratory evolution, random or directed mutagenesis, transposon-mediated gene disruption, or CRISPR interference (CRISPRi). Although any of these approaches may be applicable for identifying engineering targets, here we focus on using CRISPRi to reduce the time required to engineer more robust microbes for industrial applications. ONE-SENTENCE SUMMARY The development of genome scale CRISPR-based libraries in new microbes enables discovery of genetic factors linked to desired traits for engineering more robust microbial systems.
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Affiliation(s)
- Margaret K Bales
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Bredesen Center for Interdisciplinary Research, Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Michael Melesse Vergara
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Carrie A Eckert
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- Bredesen Center for Interdisciplinary Research, Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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8
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Xu Z, Chen S, Wu W, Wen Y, Cao H. Type I CRISPR-Cas-mediated microbial gene editing and regulation. AIMS Microbiol 2023; 9:780-800. [PMID: 38173969 PMCID: PMC10758571 DOI: 10.3934/microbiol.2023040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 12/03/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
There are six major types of CRISPR-Cas systems that provide adaptive immunity in bacteria and archaea against invasive genetic elements. The discovery of CRISPR-Cas systems has revolutionized the field of genetics in many organisms. In the past few years, exploitations of the most abundant class 1 type I CRISPR-Cas systems have revealed their great potential and distinct advantages to achieve gene editing and regulation in diverse microorganisms in spite of their complicated structures. The widespread and diversified type I CRISPR-Cas systems are becoming increasingly attractive for the development of new biotechnological tools, especially in genetically recalcitrant microbial strains. In this review article, we comprehensively summarize recent advancements in microbial gene editing and regulation by utilizing type I CRISPR-Cas systems. Importantly, to expand the microbial host range of type I CRISPR-Cas-based applications, these structurally complicated systems have been improved as transferable gene-editing tools with efficient delivery methods for stable expression of CRISPR-Cas elements, as well as convenient gene-regulation tools with the prevention of DNA cleavage by obviating deletion or mutation of the Cas3 nuclease. We envision that type I CRISPR-Cas systems will largely expand the biotechnological toolbox for microbes with medical, environmental and industrial importance.
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Affiliation(s)
- Zeling Xu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Shuzhen Chen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Weiyan Wu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Yongqi Wen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China
| | - Huiluo Cao
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
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9
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Zhang Y, Kubiak AM, Bailey TS, Claessen L, Hittmeyer P, Dubois L, Theys J, Lambin P. Development of a CRISPR-Cas12a system for efficient genome engineering in clostridia. Microbiol Spectr 2023; 11:e0245923. [PMID: 37947521 PMCID: PMC10715149 DOI: 10.1128/spectrum.02459-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 07/13/2023] [Indexed: 11/12/2023] Open
Abstract
IMPORTANCE Continued efforts in developing the CRISPR-Cas systems will further enhance our understanding and utilization of Clostridium species. This study demonstrates the development and application of a genome-engineering tool in two Clostridium strains, Clostridium butyricum and Clostridium sporogenes, which have promising potential as probiotics and oncolytic agents. Particular attention was given to the folding of precursor crRNA and the role of this process in off-target DNA cleavage by Cas12a. The results provide the guidelines necessary for efficient genome engineering using this system in clostridia. Our findings not only expand our fundamental understanding of genome-engineering tools in clostridia but also improve this technology to allow use of its full potential in a plethora of biotechnological applications.
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Affiliation(s)
- Yanchao Zhang
- M-Lab, Department of Precision Medicine, GROW - School of Oncology and Reproduction, Maastricht University, Maastricht, The Netherlands
| | - Aleksandra M. Kubiak
- M-Lab, Department of Precision Medicine, GROW - School of Oncology and Reproduction, Maastricht University, Maastricht, The Netherlands
- Exomnis Biotech BV, Maastricht, The Netherlands
| | - Tom S. Bailey
- M-Lab, Department of Precision Medicine, GROW - School of Oncology and Reproduction, Maastricht University, Maastricht, The Netherlands
| | - Luuk Claessen
- M-Lab, Department of Precision Medicine, GROW - School of Oncology and Reproduction, Maastricht University, Maastricht, The Netherlands
- LivingMed Biotech SRL, Liège, Belgium
| | - Philip Hittmeyer
- M-Lab, Department of Precision Medicine, GROW - School of Oncology and Reproduction, Maastricht University, Maastricht, The Netherlands
- LivingMed Biotech SRL, Liège, Belgium
| | - Ludwig Dubois
- M-Lab, Department of Precision Medicine, GROW - School of Oncology and Reproduction, Maastricht University, Maastricht, The Netherlands
| | - Jan Theys
- M-Lab, Department of Precision Medicine, GROW - School of Oncology and Reproduction, Maastricht University, Maastricht, The Netherlands
| | - Philippe Lambin
- M-Lab, Department of Precision Medicine, GROW - School of Oncology and Reproduction, Maastricht University, Maastricht, The Netherlands
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10
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Liu Z, Liu J, Yang Z, Zhu L, Zhu Z, Huang H, Jiang L. Endogenous CRISPR-Cas mediated in situ genome editing: State-of-the-art and the road ahead for engineering prokaryotes. Biotechnol Adv 2023; 68:108241. [PMID: 37633620 DOI: 10.1016/j.biotechadv.2023.108241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/23/2023] [Accepted: 08/23/2023] [Indexed: 08/28/2023]
Abstract
The CRISPR-Cas systems have shown tremendous promise as heterologous tools for genome editing in various prokaryotes. However, the perturbation of DNA homeostasis and the inherent toxicity of Cas9/12a proteins could easily lead to cell death, which led to the development of endogenous CRISPR-Cas systems. Programming the widespread endogenous CRISPR-Cas systems for in situ genome editing represents a promising tool in prokaryotes, especially in genetically intractable species. Here, this review briefly summarizes the advances of endogenous CRISPR-Cas-mediated genome editing, covering aspects of establishing and optimizing the genetic tools. In particular, this review presents the application of different types of endogenous CRISPR-Cas tools for strain engineering, including genome editing and genetic regulation. Notably, this review also provides a detailed discussion of the transposon-associated CRISPR-Cas systems, and the programmable RNA-guided transposition using endogenous CRISPR-Cas systems to enable editing of microbial communities for understanding and control. Therefore, they will be a powerful tool for targeted genetic manipulation. Overall, this review will not only facilitate the development of standard genetic manipulation tools for non-model prokaryotes but will also enable more non-model prokaryotes to be genetically tractable.
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Affiliation(s)
- Zhenlei Liu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Jiayu Liu
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Zhihan Yang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Liying Zhu
- College of Chemical and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Zhengming Zhu
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
| | - He Huang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210046, China.
| | - Ling Jiang
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China; State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, China.
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11
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Musilova J, Kourilova X, Hermankova K, Bezdicek M, Ieremenko A, Dvorak P, Obruca S, Sedlar K. Genomic and phenotypic comparison of polyhydroxyalkanoates producing strains of genus Caldimonas/ Schlegelella. Comput Struct Biotechnol J 2023; 21:5372-5381. [PMID: 37965057 PMCID: PMC10641440 DOI: 10.1016/j.csbj.2023.10.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 10/27/2023] [Accepted: 10/27/2023] [Indexed: 11/16/2023] Open
Abstract
Polyhydroxyalkanoates (PHAs) have emerged as an environmentally friendly alternative to conventional polyesters. In this study, we present a comprehensive analysis of the genomic and phenotypic characteristics of three non-model thermophilic bacteria known for their ability to produce PHAs: Schlegelella aquatica LMG 23380T, Caldimonas thermodepolymerans DSM 15264, and C. thermodepolymerans LMG 21645 and the results were compared with the type strain C. thermodepolymerans DSM 15344T. We have assembled the first complete genomes of these three bacteria and performed the structural and functional annotation. This analysis has provided valuable insights into the biosynthesis of PHAs and has allowed us to propose a comprehensive scheme of carbohydrate metabolism in the studied bacteria. Through phylogenomic analysis, we have confirmed the synonymity between Caldimonas and Schlegelella genera, and further demonstrated that S. aquatica and S. koreensis, currently classified as orphan species, belong to the Caldimonas genus.
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Affiliation(s)
- Jana Musilova
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czech Republic
| | - Xenie Kourilova
- Department of Food Chemistry and Biotechnology, Faculty of Chemistry, Brno University of Technology, Brno, Czech Republic
| | - Kristyna Hermankova
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czech Republic
| | - Matej Bezdicek
- Department of Internal Medicine – Hematology and Oncology, University Hospital Brno, Brno, Czech Republic
| | - Anastasiia Ieremenko
- Department of Experimental Biology (Section of Microbiology, Microbial Bioengineering Laboratory), Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Pavel Dvorak
- Department of Experimental Biology (Section of Microbiology, Microbial Bioengineering Laboratory), Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Stanislav Obruca
- Department of Food Chemistry and Biotechnology, Faculty of Chemistry, Brno University of Technology, Brno, Czech Republic
| | - Karel Sedlar
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czech Republic
- Institute of Bioinformatics, Department of Informatics, Ludwig-Maximilians-Universität München, Munich, Germany
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12
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Yang Z, Li Z, Li B, Bu R, Tan GY, Wang Z, Yan H, Xin Z, Zhang G, Li M, Xiang H, Zhang L, Wang W. A thermostable type I-B CRISPR-Cas system for orthogonal and multiplexed genetic engineering. Nat Commun 2023; 14:6193. [PMID: 37794017 PMCID: PMC10551041 DOI: 10.1038/s41467-023-41973-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 09/26/2023] [Indexed: 10/06/2023] Open
Abstract
Thermophilic cell factories have remarkably broad potential for industrial applications, but are limited by a lack of genetic manipulation tools and recalcitrance to transformation. Here, we identify a thermophilic type I-B CRISPR-Cas system from Parageobacillus thermoglucosidasius and find it displays highly efficient transcriptional repression or DNA cleavage activity that can be switched by adjusting crRNA length to less than or greater than 26 bp, respectively, without ablating Cas3 nuclease. We then develop an orthogonal tool for genome editing and transcriptional repression using this type I-B system in both thermophile and mesophile hosts. Empowered by this tool, we design a strategy to screen the genome-scale targets involved in transformation efficiency and established dynamically controlled supercompetent P. thermoglucosidasius cells with high efficiency ( ~ 108 CFU/μg DNA) by temporal multiplexed repression. We also demonstrate the construction of thermophilic riboflavin cell factory with hitherto highest titers in high temperature fermentation by genome-scale identification and combinatorial manipulation of multiple targets. This work enables diverse high-efficiency genetic manipulation in P. thermoglucosidasius and facilitates the engineering of thermophilic cell factories.
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Affiliation(s)
- Zhiheng Yang
- State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Zilong Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Bixiao Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Ruihong Bu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
- School of Medicine and Pharmacy, Ocean University of China, 266003, Qingdao, China
| | - Gao-Yi Tan
- State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
| | - Zhengduo Wang
- State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
| | - Hao Yan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Zhenguo Xin
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Guojian Zhang
- School of Medicine and Pharmacy, Ocean University of China, 266003, Qingdao, China
| | - Ming Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Lixin Zhang
- State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China.
| | - Weishan Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
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13
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Volke DC, Orsi E, Nikel PI. Emergent CRISPR-Cas-based technologies for engineering non-model bacteria. Curr Opin Microbiol 2023; 75:102353. [PMID: 37413959 DOI: 10.1016/j.mib.2023.102353] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 07/08/2023]
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated proteins (Cas) technologies brought a transformative change in the way bacterial genomes are edited, and a plethora of studies contributed to developing multiple tools based on these approaches. Prokaryotic biotechnology benefited from the implementation of such genome engineering strategies, with an increasing number of non-model bacterial species becoming genetically tractable. In this review, we summarize the recent trends in engineering non-model microbes using CRISPR-Cas technologies, discussing their potential in supporting cell factory design towards biotechnological applications. These efforts include, among other examples, genome modifications as well as tunable transcriptional regulation (both positive and negative). Moreover, we examine how CRISPR-Cas toolkits for engineering non-model organisms enabled the exploitation of emergent biotechnological processes (e.g. native and synthetic assimilation of one-carbon substrates). Finally, we discuss our slant on the future of bacterial genome engineering for domesticating non-model organisms in light of the most recent advances in the ever-expanding CRISPR-Cas field.
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Affiliation(s)
- Daniel C Volke
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Enrico Orsi
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
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14
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Olson DG, Maloney MI, Lanahan AA, Cervenka ND, Xia Y, Pech-Canul A, Hon S, Tian L, Ziegler SJ, Bomble YJ, Lynd LR. Ethanol tolerance in engineered strains of Clostridium thermocellum. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:137. [PMID: 37710260 PMCID: PMC10503014 DOI: 10.1186/s13068-023-02379-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 08/05/2023] [Indexed: 09/16/2023]
Abstract
Clostridium thermocellum is a natively cellulolytic bacterium that is promising candidate for cellulosic biofuel production, and can produce ethanol at high yields (75-80% of theoretical) but the ethanol titers produced thus far are too low for commercial application. In several strains of C. thermocellum engineered for increased ethanol yield, ethanol titer seems to be limited by ethanol tolerance. Previous work to improve ethanol tolerance has focused on the WT organism. In this work, we focused on understanding ethanol tolerance in several engineered strains of C. thermocellum. We observed a tradeoff between ethanol tolerance and production. Adaptation for increased ethanol tolerance decreases ethanol production. Second, we observed a consistent genetic response to ethanol stress involving mutations at the AdhE locus. These mutations typically reduced NADH-linked ADH activity. About half of the ethanol tolerance phenotype could be attributed to the elimination of NADH-linked activity based on a targeted deletion of adhE. Finally, we observed that rich growth medium increases ethanol tolerance, but this effect is eliminated in an adhE deletion strain. Together, these suggest that ethanol inhibits growth and metabolism via a redox-imbalance mechanism. The improved understanding of mechanisms of ethanol tolerance described here lays a foundation for developing strains of C. thermocellum with improved ethanol production.
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Affiliation(s)
- Daniel G Olson
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA.
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA.
| | - Marybeth I Maloney
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Anthony A Lanahan
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Nicholas D Cervenka
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Ying Xia
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA
- College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China
| | - Angel Pech-Canul
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Shuen Hon
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Liang Tian
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
- Youth Olympic Village, #1-1-602, Jianye District, Nanjing, Jiangsu, China
| | - Samantha J Ziegler
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Yannick J Bomble
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
- National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Lee R Lynd
- Thayer School of Engineering at Dartmouth College, Hanover, NH, 03755, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
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15
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Moenaert A, Bjornsdottir B, Haraldsson EB, Allahgholi L, Zieri A, Zangl I, Sigurðardóttir S, Örlygsson J, Nordberg Karlsson E, Friðjónsson ÓH, Hreggviðsson GÓ. Metabolic engineering of Thermoanaerobacterium AK17 for increased ethanol production in seaweed hydrolysate. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:135. [PMID: 37697400 PMCID: PMC10496261 DOI: 10.1186/s13068-023-02388-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/01/2023] [Indexed: 09/13/2023]
Abstract
Sustainably produced renewable biomass has the potential to replace fossil-based feedstocks, for generation of biobased fuels and chemicals of industrial interest, in biorefineries. In this context, seaweeds contain a large fraction of carbohydrates that are a promising source for enzymatic and/or microbial biorefinery conversions. The thermoanaerobe Thermoanaerobacterium AK17 is a versatile fermentative bacterium producing ethanol, acetate and lactate from various sugars. In this study, strain AK17 was engineered for more efficient production of ethanol by knocking out the lactate and acetate side-product pathways. This was successfully achieved, but the strain reverted to acetate production by recruiting enzymes from the butyrate pathway. Subsequently this pathway was knocked out and the resultant strain AK17_M6 could produce ethanol close to the maximum theoretical yield (90%), leading to a 1.5-fold increase in production compared to the wild-type strain. Strain AK17 was also shown to successfully ferment brown seaweed hydrolysate from Laminaria digitata to ethanol in a comparatively high yield of 0.45 g/g substrate, with the primary carbon sources for the fermentations being mannitol, laminarin-derived glucose and short laminari-oligosaccharides. As strain AK17 was successfully engineered and has a wide carbohydrate utilization range that includes mannitol from brown seaweed, as well as hexoses and pentoses found in both seaweeds and lignocellulose, the new strain AK17_M6 obtained in this study is an interesting candidate for production of ethanol from both second and third generations biomass.
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Affiliation(s)
- Antoine Moenaert
- Department of Biotechnology, Matís Ohf, Reykjavík, Iceland.
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland.
| | | | - Einar Baldvin Haraldsson
- Department of Biotechnology, Matís Ohf, Reykjavík, Iceland
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
| | - Leila Allahgholi
- Biotechnology, Department of Chemistry, Lund University, Lund, Sweden
| | - Anna Zieri
- IMC University of Applied Sciences Krems, Krems, Austria
| | - Isabella Zangl
- IMC University of Applied Sciences Krems, Krems, Austria
| | | | - Jóhann Örlygsson
- Faculty of Natural Resource Sciences, University of Akureyri, Akureyri, Iceland
| | | | - Ólafur H Friðjónsson
- Department of Biotechnology, Matís Ohf, Reykjavík, Iceland
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
| | - Guðmundur Óli Hreggviðsson
- Department of Biotechnology, Matís Ohf, Reykjavík, Iceland
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
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16
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Chen S, Cao H, Xu Z, Huang J, Liu Z, Li T, Duan C, Wu W, Wen Y, Zhang LH, Xu Z. A type I-F CRISPRi system unveils the novel role of CzcR in modulating multidrug resistance of Pseudomonas aeruginosa. Microbiol Spectr 2023; 11:e0112323. [PMID: 37646520 PMCID: PMC10581170 DOI: 10.1128/spectrum.01123-23] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 07/16/2023] [Indexed: 09/01/2023] Open
Abstract
Pseudomonas aeruginosa has abundant signaling systems that exquisitely control its antibiotic resistance in response to different environmental cues. Understanding the regulation of antibiotic resistance will provide important implications for precise antimicrobial interventions. However, efficient genetic tools for functional gene characterizations are sometimes not available, particularly, in clinically isolated strains. Here, we established a type I-F CRISPRi (CSYi) system for programmable gene silencing. By incorporating anti-CRISPR proteins, this system was even applicable to bacterial hosts encoding a native type I-F CRISPR-Cas system. With the newly developed gene-silencing system, we revealed that the response regulator CzcR from the zinc (Zn2+)-responsive two-component system CzcS/CzcR is a repressor of efflux pumps MexAB-OprM and MexGHI-OpmD, which inhibits the expression of both operons by directly interacting with their promoters. Repression of MexAB-OprM consequently increases the susceptibility of P. aeruginosa to multiple antibiotics such as levofloxacin and amikacin. Together, this study provided a simple approach to study gene functions, which enabled us to unveil the novel role of CzcR in modulating efflux pump genes and multidrug resistance in P. aeruginosa. IMPORTANCE P. aeruginosa is a ubiquitous opportunistic pathogen frequently causing chronic infections. In addition to being an important model organism for antibiotic-resistant research, this species is also important for understanding and exploiting CRISPR-Cas systems. In this study, we established a gene-silencing system based on the most abundant type I-F CRISPR-Cas system in this species, which can be readily employed to achieve targeted gene repression in multiple bacterial species. Using this gene-silencing system, the physiological role of Zn2+ and its responsive regulator CzcR in modulating multidrug resistance was unveiled with great convenience. This study not only displayed a new framework to expand the abundant CRISPR-Cas and anti-CRISPR systems for functional gene characterizations but also provided new insights into the regulation of multidrug resistance in P. aeruginosa and important clues for precise anti-pseudomonal therapies.
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Affiliation(s)
- Shuzhen Chen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Huiluo Cao
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Zirui Xu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Jiahui Huang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Zhiqing Liu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Ting Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Cheng Duan
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Weiyan Wu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Yongqi Wen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Lian-Hui Zhang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
| | - Zeling Xu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
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17
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Poulalier-Delavelle M, Baker JP, Millard J, Winzer K, Minton NP. Endogenous CRISPR/Cas systems for genome engineering in the acetogens Acetobacterium woodii and Clostridium autoethanogenum. Front Bioeng Biotechnol 2023; 11:1213236. [PMID: 37425362 PMCID: PMC10328091 DOI: 10.3389/fbioe.2023.1213236] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/06/2023] [Indexed: 07/11/2023] Open
Abstract
Acetogenic bacteria can play a major role in achieving Net Zero through their ability to convert CO2 into industrially relevant chemicals and fuels. Full exploitation of this potential will be reliant on effective metabolic engineering tools, such as those based on the Streptococcus pyogenes CRISPR/Cas9 system. However, attempts to introduce cas9-containing vectors into Acetobacterium woodii were unsuccessful, most likely as a consequence of Cas9 nuclease toxicity and the presence of a recognition site for an endogenous A. woodii restriction-modification (R-M) system in the cas9 gene. As an alternative, this study aims to facilitate the exploitation of CRISPR/Cas endogenous systems as genome engineering tools. Accordingly, a Python script was developed to automate the prediction of protospacer adjacent motif (PAM) sequences and used to identify PAM candidates of the A. woodii Type I-B CRISPR/Cas system. The identified PAMs and the native leader sequence were characterized in vivo by interference assay and RT-qPCR, respectively. Expression of synthetic CRISPR arrays, consisting of the native leader sequence, direct repeats, and adequate spacer, along with an editing template for homologous recombination, successfully led to the creation of 300 bp and 354 bp in-frame deletions of pyrE and pheA, respectively. To further validate the method, a 3.2 kb deletion of hsdR1 was also generated, as well as the knock-in of the fluorescence-activating and absorption-shifting tag (FAST) reporter gene at the pheA locus. Homology arm length, cell density, and the amount of DNA used for transformation were found to significantly impact editing efficiencies. The devised workflow was subsequently applied to the Type I-B CRISPR/Cas system of Clostridium autoethanogenum, enabling the generation of a 561 bp in-frame deletion of pyrE with 100% editing efficiency. This is the first report of genome engineering of both A. woodii and C. autoethanogenum using their endogenous CRISPR/Cas systems.
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Affiliation(s)
| | | | | | | | - Nigel P. Minton
- *Correspondence: Margaux Poulalier-Delavelle, ; Nigel P. Minton,
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18
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Hussain MS, Anand V, Kumar M. Functional PAM sequence for DNA interference by CRISPR-Cas I-B system of Leptospira interrogans and the role of LinCas11b encoded within lincas8b. Int J Biol Macromol 2023; 237:124086. [PMID: 36940764 DOI: 10.1016/j.ijbiomac.2023.124086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/18/2023] [Accepted: 03/15/2023] [Indexed: 03/23/2023]
Abstract
Pathogenic species of Leptospira are recalcitrant for genetic manipulation using conventional tools, and therefore there is a need to explore techniques of higher efficiency. Application of endogenous CRISPR-Cas tool is emerging and efficient; nevertheless, it is limited by a poor understanding of interference machinery in the bacterial genome and its associated protospacer adjacent motif (PAM). In this study, interference machinery of CRISPR-Cas subtype I-B (Lin_I-B) from L. interrogans was experimentally validated in E. coli using the various identified PAM (TGA, ATG, ATA). The overexpression of the Lin_I-B interference machinery in E. coli demonstrated that LinCas5, LinCas6, LinCas7, and LinCas8b can self-assemble on cognate CRISPR RNA to form an interference complex (LinCascade). Moreover, a robust interference of target plasmids containing a protospacer with a PAM suggested a functional LinCascade. We also recognized a small open reading frame within lincas8b that independently co-translates LinCas11b. A mutant variant of LinCascade-Cas11b that lacks LinCas11b co-expression erred to mount target plasmid interference. At the same time, LinCas11b complementation in LinCascade-Cas11b rescued target plasmid interference. Thus, the present study establishes Leptospira subtype I-B interference machinery to be functional and, soon, may pave the way for scientists to harness it as a programmable endogenous genetic manipulation tool.
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Affiliation(s)
- Md Saddam Hussain
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Vineet Anand
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Manish Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
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19
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Ye JW, Lin YN, Yi XQ, Yu ZX, Liu X, Chen GQ. Synthetic biology of extremophiles: a new wave of biomanufacturing. Trends Biotechnol 2023; 41:342-357. [PMID: 36535816 DOI: 10.1016/j.tibtech.2022.11.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/12/2022] [Accepted: 11/25/2022] [Indexed: 12/23/2022]
Abstract
Microbial biomanufacturing, powered by the advances of synthetic biology, has attracted growing interest for the production of diverse products. In contrast to conventional microbes, extremophiles have shown better performance for low-cost production owing to their outstanding growth and synthesis capacity under stress conditions, allowing unsterilized fermentation processes. We review increasing numbers of products already manufactured utilizing extremophiles in recent years. In addition, genetic parts, molecular tools, and manipulation approaches for extremophile engineering are also summarized, and challenges and opportunities are predicted for non-conventional chassis. Next-generation industrial biotechnology (NGIB) based on engineered extremophiles promises to simplify biomanufacturing processes and achieve open and continuous fermentation, without sterilization, and utilizing low-cost substrates, making NGIB an attractive green process for sustainable manufacturing.
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Affiliation(s)
- Jian-Wen Ye
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China; Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China; Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Yi-Na Lin
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China; Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China; Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Xue-Qing Yi
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhuo-Xuan Yu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, China
| | - Xu Liu
- PhaBuilder Biotech Company, Shunyi District, Zhaoquan Ying, Beijing 101309, China
| | - Guo-Qiang Chen
- School of Life Sciences, Tsinghua University, Beijing 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; Ministry of Education (MOE) Laboratory of Industrial Biocatalysis, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Center for Life Sciences, Beijing, China.
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20
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Wang J, Wei J, Li H, Li Y. High-efficiency genome editing of an extreme thermophile Thermus thermophilus using endogenous type I and type III CRISPR-Cas systems. MLIFE 2022; 1:412-427. [PMID: 38818488 PMCID: PMC10989782 DOI: 10.1002/mlf2.12045] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 10/13/2022] [Accepted: 10/15/2022] [Indexed: 06/01/2024]
Abstract
Thermus thermophilus is an attractive species in the bioindustry due to its valuable natural products, abundant thermophilic enzymes, and promising fermentation capacities. However, efficient and versatile genome editing tools are not available for this species. In this study, we developed an efficient genome editing tool for T. thermophilus HB27 based on its endogenous type I-B, I-C, and III-A/B CRISPR-Cas systems. First, we systematically characterized the DNA interference capabilities of the different types of the native CRISPR-Cas systems in T. thermophilus HB27. We found that genomic manipulations such as gene deletion, mutation, and in situ tagging could be easily implemented by a series of genome-editing plasmids carrying an artificial self-targeting mini-CRISPR and a donor DNA responsible for the recombinant recovery. We also compared the genome editing efficiency of different CRISPR-Cas systems and the editing plasmids with donor DNAs of different lengths. Additionally, we developed a reporter gene system for T. thermophilus based on a heat-stable β-galactosidase gene TTP0042, and constructed an engineered strain with a high production capacity of superoxide dismutases by genome modification.
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Affiliation(s)
- Jinting Wang
- State Key Laboratory of Agricultural Microbiology and College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- Shenzhen Institute of Nutrition and HealthHuazhong Agricultural UniversityShenzhenChina
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at ShenzhenChinese Academy of Agricultural SciencesShenzhenChina
| | - Junwei Wei
- State Key Laboratory of Agricultural Microbiology and College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- Shenzhen Institute of Nutrition and HealthHuazhong Agricultural UniversityShenzhenChina
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at ShenzhenChinese Academy of Agricultural SciencesShenzhenChina
| | - Haijuan Li
- College of Biological and Environmental EngineeringXi'an UniversityXi'anChina
| | - Yingjun Li
- State Key Laboratory of Agricultural Microbiology and College of Life Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- Shenzhen Institute of Nutrition and HealthHuazhong Agricultural UniversityShenzhenChina
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at ShenzhenChinese Academy of Agricultural SciencesShenzhenChina
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21
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Exploiting the Type I-B CRISPR Genome Editing System in Thermoanaerobacterium aotearoense SCUT27 and Engineering the Strain for Enhanced Ethanol Production. Appl Environ Microbiol 2022; 88:e0075122. [PMID: 35862665 PMCID: PMC9361813 DOI: 10.1128/aem.00751-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Thermoanaerobacterium aotearoense strain SCUT27 is a potential industrial biofuel-producing strain because of its broad substrate spectrum, especially the ability to co-use glucose and xylose. The bottleneck hindering the development of strain SCUT27 is the lack of selective markers for polygene manipulation in this thermophilic bacterium. In this study, the endogenous type I-B clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) system was developed for multiplex genome editing of strain SCUT27. The protospacer-adjacent motif was identified by in silico analysis and verified with orotidine-5'-phosphate decarboxylase (pyrF) or lactate dehydrogenase (ldh) as the editing target. The type I-B CRISPR/Cas system was functional in strain SCUT27 with 58.3% to 100% editing efficiency. A multiplex genome editing method based on thymidine kinase (tdk) as a negative selection marker was developed, and strain SCUT27/Δtdk/Δldh/ΔargR, in which ldh and the arginine repressor (argR) were knocked out successively, was successfully obtained. Strain SCUT27/Δtdk/Δldh/ΔargR exhibited prominent advantages over wild-type SCUT27 in ethanol production, with significantly improved ability to metabolize xylose. IMPORTANCE Thermophilic microbes have attracted great attention as potential candidates for production of biofuels and chemicals from lignocellulose because of their thermal tolerance and wide substrate spectra. The ability to edit multiple genes using the native type I-B CRISPR/Cas system would speed up engineering of Thermoanaerobacterium aotearoense strain SCUT27 for higher ethanol production from lignocellulosic hydrolysates. Here, we produced a mutant strain, T. aotearoense SCUT27/Δtdk/Δldh/ΔargR, using the native CRISPR/Cas system. The engineered strain showed satisfactory performance with improved ethanol productivity from various lignocellulosic hydrolysates. Our data lay the foundations for development of this thermophilic microbe into an excellent ethanol producer using lignocellulosic hydrolysates. The methods described here may also provide a reference to develop multigene editing methods for other microorganisms.
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Le Y, Sun J. CRISPR/Cas genome editing systems in thermophiles: Current status, associated challenges, and future perspectives. ADVANCES IN APPLIED MICROBIOLOGY 2022; 118:1-30. [PMID: 35461662 DOI: 10.1016/bs.aambs.2022.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Thermophiles, offering an attractive and unique platform for a broad range of applications in biofuels and environment protections, have received a significant attention and growing interest from academy and industry. However, the exploration and exploitation of thermophilic organisms have been hampered by the lack of a powerful genome manipulation tool to improve production efficiency. At current, the clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/CRISPR associated (Cas) system has been successfully exploited as a competent, simplistic, and powerful tool for genome engineering both in eukaryotes and prokaryotes. Indeed, with the significant efforts made in recent years, some thermostable Cas9 proteins have been well identified and characterized and further, some thermostable Cas9-based editing tools have been successfully established in some representative obligate thermophiles. In this regard, we reviewed the current status and its progress in CRISPR/Cas-based genome editing system towards a variety of thermophilic organisms. Despite the potentials of these progresses, multiple factors/barriers still have to be overcome and optimized for improving its editing efficiency in thermophiles. Some insights into the roles of thermostable CRISPR/Cas technologies for the metabolic engineering of thermophiles as a thermophilic microbial cell factory were also fully analyzed and discussed.
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Affiliation(s)
- Yilin Le
- Biofuels institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China.
| | - Jianzhong Sun
- Biofuels institute, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China.
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Ganguly J, Martin-Pascual M, Montiel González D, Bulut A, Vermeulen B, Tjalma I, Vidaki A, van Kranenburg R. Breaking the Restriction Barriers and Applying CRISPRi as a Gene Silencing Tool in Pseudoclostridium thermosuccinogenes. Microorganisms 2022; 10:698. [PMID: 35456750 PMCID: PMC9044749 DOI: 10.3390/microorganisms10040698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 12/10/2022] Open
Abstract
Pseudoclostridium thermosuccinogenes is a thermophilic bacterium capable of producing succinate from lignocellulosic-derived sugars and has the potential to be exploited as a platform organism. However, exploitation of P. thermosuccinogenes has been limited partly due to the genetic inaccessibility and lack of genome engineering tools. In this study, we established the genetic accessibility for P. thermosuccinogenes DSM 5809. By overcoming restriction barriers, transformation efficiencies of 102 CFU/µg plasmid DNA were achieved. To this end, the plasmid DNA was methylated in vivo when transformed into an engineered E. coli HST04 strain expressing three native methylation systems of the thermophile. This protocol was used to introduce a ThermodCas9-based CRISPRi tool targeting the gene encoding malic enzyme in P. thermosuccinogenes, demonstrating the principle of gene silencing. This resulted in 75% downregulation of its expression and had an impact on the strain's fermentation profile. Although the details of the functioning of the restriction modification systems require further study, in vivo methylation can already be applied to improve transformation efficiency of P. thermosuccinogenes. Making use of the ThermodCas9-based CRISPRi, this is the first example demonstrating that genetic engineering in P. thermosuccinogenes is feasible and establishing the way for metabolic engineering of this bacterium.
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Affiliation(s)
| | - Maria Martin-Pascual
- Laboratory of Microbiology, Wageningen University and Research, 6708 WE Wageningen, The Netherlands; (M.M.-P.); (B.V.); (I.T.)
| | - Diego Montiel González
- Department of Genetic Identification, Erasmus MC University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands; (D.M.G.); (A.V.)
| | - Alkan Bulut
- Fontys University of Applied Sciences, 5612 AR Eindhoven, The Netherlands;
| | - Bram Vermeulen
- Laboratory of Microbiology, Wageningen University and Research, 6708 WE Wageningen, The Netherlands; (M.M.-P.); (B.V.); (I.T.)
| | - Ivo Tjalma
- Laboratory of Microbiology, Wageningen University and Research, 6708 WE Wageningen, The Netherlands; (M.M.-P.); (B.V.); (I.T.)
| | - Athina Vidaki
- Department of Genetic Identification, Erasmus MC University Medical Center Rotterdam, 3015 GD Rotterdam, The Netherlands; (D.M.G.); (A.V.)
| | - Richard van Kranenburg
- Corbion, 4206 AC Gorinchem, The Netherlands;
- Laboratory of Microbiology, Wageningen University and Research, 6708 WE Wageningen, The Netherlands; (M.M.-P.); (B.V.); (I.T.)
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24
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Rybnicky GA, Fackler NA, Karim AS, Köpke M, Jewett MC. Spacer2PAM: A computational framework to guide experimental determination of functional CRISPR-Cas system PAM sequences. Nucleic Acids Res 2022; 50:3523-3534. [PMID: 35258601 PMCID: PMC8990532 DOI: 10.1093/nar/gkac142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 02/12/2022] [Accepted: 02/15/2022] [Indexed: 11/17/2022] Open
Abstract
RNA-guided nucleases from CRISPR-Cas systems expand opportunities for precise, targeted genome modification. Endogenous CRISPR-Cas systems in many prokaryotes are attractive to circumvent expression, functionality, and unintended activity hurdles posed by heterologous CRISPR-Cas effectors. However, each CRISPR-Cas system recognizes a unique set of protospacer adjacent motifs (PAMs), which requires identification by extensive screening of randomized DNA libraries. This challenge hinders development of endogenous CRISPR-Cas systems, especially those based on multi-protein effectors and in organisms that are slow-growing or have transformation idiosyncrasies. To address this challenge, we present Spacer2PAM, an easy-to-use, easy-to-interpret R package built to predict and guide experimental determination of functional PAM sequences for any CRISPR-Cas system given its corresponding CRISPR array as input. Spacer2PAM can be used in a 'Quick' method to generate a single PAM prediction or in a 'Comprehensive' method to inform targeted PAM libraries small enough to screen in difficult to transform organisms. We demonstrate Spacer2PAM by predicting PAM sequences for industrially relevant organisms and experimentally identifying seven PAM sequences that mediate interference from the Spacer2PAM-informed PAM library for the type I-B CRISPR-Cas system from Clostridium autoethanogenum. We anticipate that Spacer2PAM will facilitate the use of endogenous CRISPR-Cas systems for industrial biotechnology and synthetic biology.
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Affiliation(s)
- Grant A Rybnicky
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, 60208, USA,Center for Synthetic Biology, Northwestern University, Evanston, IL, 60208, USA,Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, IL, 60208, USA
| | | | - Ashty S Karim
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, 60208, USA,Center for Synthetic Biology, Northwestern University, Evanston, IL, 60208, USA,Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
| | | | - Michael C Jewett
- To whom correspondence should be addressed. Tel: +1 847 467 5007; Fax: +1 847 467 5007;
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A Single Nucleotide Change in the polC DNA Polymerase III in Clostridium thermocellum Is Sufficient To Create a Hypermutator Phenotype. Appl Environ Microbiol 2022; 88:e0153121. [PMID: 35015978 DOI: 10.1128/aem.01531-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium thermocellum is a thermophilic, anaerobic bacterium that natively ferments cellulose to ethanol and is a candidate for cellulosic biofuel production. Recently, we identified a hypermutator strain of C. thermocellum with a C669Y mutation in the polC gene, which encodes a DNA polymerase III enzyme. Here, we reintroduced this mutation using recently developed CRISPR tools to demonstrate that this mutation is sufficient to recreate the hypermutator phenotype. The resulting strain shows an approximately 30-fold increase in the mutation rate. This mutation is hypothesized to function by interfering with metal ion coordination in the PHP (polymerase and histidinol phosphatase) domain, which is responsible for proofreading. The ability to selectively increase the mutation rate in C. thermocellum is a useful tool for future directed evolution experiments. IMPORTANCE Cellulosic biofuels are a promising approach to decarbonize the heavy-duty-transportation sector. A longstanding barrier to cost-effective cellulosic biofuel production is the recalcitrance of cellulose to solubilization. Native cellulose-consuming organisms, such as Clostridium thermocellum, are promising candidates for cellulosic biofuel production; however, they often need to be genetically modified to improve product formation. One approach is adaptive laboratory evolution. Our findings demonstrate a way to increase the mutation rate in this industrially relevant organism, which can reduce the time needed for adaptive evolution experiments.
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Obruča S, Dvořák P, Sedláček P, Koller M, Sedlář K, Pernicová I, Šafránek D. Polyhydroxyalkanoates synthesis by halophiles and thermophiles: towards sustainable production of microbial bioplastics. Biotechnol Adv 2022; 58:107906. [DOI: 10.1016/j.biotechadv.2022.107906] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/15/2021] [Accepted: 01/07/2022] [Indexed: 01/10/2023]
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27
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Dong H, Cui Y, Zhang D. CRISPR/Cas Technologies and Their Applications in Escherichia coli. Front Bioeng Biotechnol 2021; 9:762676. [PMID: 34858961 PMCID: PMC8632213 DOI: 10.3389/fbioe.2021.762676] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 10/20/2021] [Indexed: 11/22/2022] Open
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) systems have revolutionized genome editing and greatly promoted the development of biotechnology. However, these systems unfortunately have not been developed and applied in bacteria as extensively as in eukaryotic organism. Here, the research progress on the most widely used CRISPR/Cas tools and their applications in Escherichia coli is summarized. Genome editing based on homologous recombination, non-homologous DNA end-joining, transposons, and base editors are discussed. Finally, the state of the art of transcriptional regulation using CRISPRi is briefly reviewed. This review provides a useful reference for the application of CRISPR/Cas systems in other bacterial species.
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Affiliation(s)
- Huina Dong
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Yali Cui
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- University of Chinese Academy of Sciences, Beijing, China
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28
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Current Progress in Production of Building-Block Organic Acids by Consolidated Bioprocessing of Lignocellulose. FERMENTATION-BASEL 2021. [DOI: 10.3390/fermentation7040248] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Several organic acids have been indicated among the top value chemicals from biomass. Lignocellulose is among the most attractive feedstocks for biorefining processes owing to its high abundance and low cost. However, its highly complex nature and recalcitrance to biodegradation hinder development of cost-competitive fermentation processes. Here, current progress in development of single-pot fermentation (i.e., consolidated bioprocessing, CBP) of lignocellulosic biomass to high value organic acids will be examined, based on the potential of this approach to dramatically reduce process costs. Different strategies for CBP development will be considered such as: (i) design of microbial consortia consisting of (hemi)cellulolytic and valuable-compound producing strains; (ii) engineering of microorganisms that combine biomass-degrading and high-value compound-producing properties in a single strain. The present review will mainly focus on production of organic acids with application as building block chemicals (e.g., adipic, cis,cis-muconic, fumaric, itaconic, lactic, malic, and succinic acid) since polymer synthesis constitutes the largest sector in the chemical industry. Current research advances will be illustrated together with challenges and perspectives for future investigations. In addition, attention will be dedicated to development of acid tolerant microorganisms, an essential feature for improving titer and productivity of fermentative production of acids.
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29
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Vink JNA, Baijens JHL, Brouns SJJ. PAM-repeat associations and spacer selection preferences in single and co-occurring CRISPR-Cas systems. Genome Biol 2021; 22:281. [PMID: 34593010 PMCID: PMC8482600 DOI: 10.1186/s13059-021-02495-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 09/09/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The adaptive CRISPR-Cas immune system stores sequences from past invaders as spacers in CRISPR arrays and thereby provides direct evidence that links invaders to hosts. Mapping CRISPR spacers has revealed many aspects of CRISPR-Cas biology, including target requirements such as the protospacer adjacent motif (PAM). However, studies have so far been limited by a low number of mapped spacers in the database. RESULTS By using vast metagenomic sequence databases, we map approximately one-third of more than 200,000 unique CRISPR spacers from a variety of microbes and derive a catalog of more than two hundred unique PAM sequences associated with specific CRISPR-Cas subtypes. These PAMs are further used to correctly assign the orientation of CRISPR arrays, revealing conserved patterns between the last nucleotides of the CRISPR repeat and PAM. We could also deduce CRISPR-Cas subtype-specific preferences for targeting either template or coding strand of open reading frames. While some DNA-targeting systems (type I-E and type II systems) prefer the template strand and avoid mRNA, other DNA- and RNA-targeting systems (types I-A and I-B and type III systems) prefer the coding strand and mRNA. In addition, we find large-scale evidence that both CRISPR-Cas adaptation machinery and CRISPR arrays are shared between different CRISPR-Cas systems. This could lead to simultaneous DNA and RNA targeting of invaders, which may be effective at combating mobile genetic invaders. CONCLUSIONS This study has broad implications for our understanding of how CRISPR-Cas systems work in a wide range of organisms for which only the genome sequence is known.
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Affiliation(s)
- Jochem N A Vink
- Department of Bionanoscience, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft, The Netherlands
| | - Jan H L Baijens
- Department of Bionanoscience, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft, The Netherlands
| | - Stan J J Brouns
- Department of Bionanoscience, Delft University of Technology, Delft, The Netherlands.
- Kavli Institute of Nanoscience, Delft, The Netherlands.
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30
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Hebdon SD, Gerritsen AT, Chen YP, Marcano JG, Chou KJ. Genome-Wide Transcription Factor DNA Binding Sites and Gene Regulatory Networks in Clostridium thermocellum. Front Microbiol 2021; 12:695517. [PMID: 34566906 PMCID: PMC8457756 DOI: 10.3389/fmicb.2021.695517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 07/27/2021] [Indexed: 12/02/2022] Open
Abstract
Clostridium thermocellum is a thermophilic bacterium recognized for its natural ability to effectively deconstruct cellulosic biomass. While there is a large body of studies on the genetic engineering of this bacterium and its physiology to-date, there is limited knowledge in the transcriptional regulation in this organism and thermophilic bacteria in general. The study herein is the first report of a large-scale application of DNA-affinity purification sequencing (DAP-seq) to transcription factors (TFs) from a bacterium. We applied DAP-seq to > 90 TFs in C. thermocellum and detected genome-wide binding sites for 11 of them. We then compiled and aligned DNA binding sequences from these TFs to deduce the primary DNA-binding sequence motifs for each TF. These binding motifs are further validated with electrophoretic mobility shift assay (EMSA) and are used to identify individual TFs’ regulatory targets in C. thermocellum. Our results led to the discovery of novel, uncharacterized TFs as well as homologues of previously studied TFs including RexA-, LexA-, and LacI-type TFs. We then used these data to reconstruct gene regulatory networks for the 11 TFs individually, which resulted in a global network encompassing the TFs with some interconnections. As gene regulation governs and constrains how bacteria behave, our findings shed light on the roles of TFs delineated by their regulons, and potentially provides a means to enable rational, advanced genetic engineering of C. thermocellum and other organisms alike toward a desired phenotype.
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Affiliation(s)
- Skyler D Hebdon
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Alida T Gerritsen
- Computational Sciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Yi-Pei Chen
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Joan G Marcano
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Katherine J Chou
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
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31
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Joseph RC, Kelley SQ, Kim NM, Sandoval NR. Metabolic Engineering and the Synthetic Biology Toolbox for
Clostridium. Metab Eng 2021. [DOI: 10.1002/9783527823468.ch16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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32
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Xu Z, Li Y, Cao H, Si M, Zhang G, Woo PCY, Yan A. A transferrable and integrative type I-F Cascade for heterologous genome editing and transcription modulation. Nucleic Acids Res 2021; 49:e94. [PMID: 34157103 PMCID: PMC8450077 DOI: 10.1093/nar/gkab521] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 05/18/2021] [Accepted: 06/05/2021] [Indexed: 12/31/2022] Open
Abstract
The Class 1 type I CRISPR–Cas systems represent the most abundant and diverse CRISPR systems in nature. However, their applications for generic genome editing have been hindered due to difficulties of introducing the class-specific, multi-component effectors (Cascade) in heterologous hosts for functioning. Here we established a transferrable Cascade system that enables stable integration and expression of a highly active type I-F Cascade in heterologous bacterial hosts for various genetic exploitations. Using the genetically recalcitrant Pseudomonas species as a paradigm, we show that the transferred Cascade displayed substantially higher DNA interference activity and greater editing capacity than both the integrative and plasmid-borne Cas9 systems, and enabled deletion of large fragments such as the 21-kb integrated cassette with efficiency and simplicity. An advanced I-F-λred system was further developed to enable editing in genotypes with poor homologous recombination capacity, clinical isolates lacking sequence information, and cells containing anti-CRISPR elements Acrs. Lastly, an ‘all-in-one’ I-F Cascade-mediated CRISPRi platform was developed for transcription modulation by simultaneous introduction of the Cascade and the programmed mini-CRISPR array in one-step. This study provides a framework for expanding the diverse type I Cascades for widespread, heterologous genome editing and establishment of editing techniques in ‘non-model’ bacterial species.
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Affiliation(s)
- Zeling Xu
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.,Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, Guangdong, China
| | - Yanran Li
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Huiluo Cao
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Meiru Si
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.,School of Biological Sciences, Qufu Normal University, Qufu, Shandong, China
| | - Guangming Zhang
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Patrick C Y Woo
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Aixin Yan
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
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Li M, Gong L, Cheng F, Yu H, Zhao D, Wang R, Wang T, Zhang S, Zhou J, Shmakov SA, Koonin EV, Xiang H. Toxin-antitoxin RNA pairs safeguard CRISPR-Cas systems. Science 2021; 372:372/6541/eabe5601. [PMID: 33926924 DOI: 10.1126/science.abe5601] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 12/29/2020] [Accepted: 03/10/2021] [Indexed: 12/18/2022]
Abstract
CRISPR-Cas systems provide RNA-guided adaptive immunity in prokaryotes. We report that the multisubunit CRISPR effector Cascade transcriptionally regulates a toxin-antitoxin RNA pair, CreTA. CreT (Cascade-repressed toxin) is a bacteriostatic RNA that sequesters the rare arginine tRNAUCU (transfer RNA with anticodon UCU). CreA is a CRISPR RNA-resembling antitoxin RNA, which requires Cas6 for maturation. The partial complementarity between CreA and the creT promoter directs Cascade to repress toxin transcription. Thus, CreA becomes antitoxic only in the presence of Cascade. In CreTA-deleted cells, cascade genes become susceptible to disruption by transposable elements. We uncover several CreTA analogs associated with diverse archaeal and bacterial CRISPR-cas loci. Thus, toxin-antitoxin RNA pairs can safeguard CRISPR immunity by making cells addicted to CRISPR-Cas, which highlights the multifunctionality of Cas proteins and the intricate mechanisms of CRISPR-Cas regulation.
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Affiliation(s)
- Ming Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China. .,CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Luyao Gong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Feiyue Cheng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Haiying Yu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Dahe Zhao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Rui Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Tian Wang
- College of Life Sciences, Sichuan Normal University, Chengdu, China
| | - Shengjie Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Jian Zhou
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Sergey A Shmakov
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China. .,College of Life Science, University of Chinese Academy of Sciences, Beijing, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
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Efficient genome editing of an extreme thermophile, Thermus thermophilus, using a thermostable Cas9 variant. Sci Rep 2021; 11:9586. [PMID: 33953310 PMCID: PMC8100143 DOI: 10.1038/s41598-021-89029-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 04/20/2021] [Indexed: 02/03/2023] Open
Abstract
Thermophilic organisms are extensively studied in industrial biotechnology, for exploration of the limits of life, and in other contexts. Their optimal growth at high temperatures presents a challenge for the development of genetic tools for their genome editing, since genetic markers and selection substrates are often thermolabile. We sought to develop a thermostable CRISPR-Cas9 based system for genome editing of thermophiles. We identified CaldoCas9 and designed an associated guide RNA and showed that the pair have targetable nuclease activity in vitro at temperatures up to 65 °C. We performed a detailed characterization of the protospacer adjacent motif specificity of CaldoCas9, which revealed a preference for 5'-NNNNGNMA. We constructed a plasmid vector for the delivery and use of the CaldoCas9 based genome editing system in the extreme thermophile Thermus thermophilus at 65 °C. Using the vector, we generated gene knock-out mutants of T. thermophilus, targeting genes on the bacterial chromosome and megaplasmid. Mutants were obtained at a frequency of about 90%. We demonstrated that the vector can be cured from mutants for a subsequent round of genome editing. CRISPR-Cas9 based genome editing has not been reported previously in the extreme thermophile T. thermophilus. These results may facilitate development of genome editing tools for other extreme thermophiles and to that end, the vector has been made available via the plasmid repository Addgene.
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Zhou X, Wang X, Luo H, Wang Y, Wang Y, Tu T, Qin X, Su X, Bai Y, Yao B, Huang H, Zhang J. Exploiting heterologous and endogenous CRISPR-Cas systems for genome editing in the probiotic Clostridium butyricum. Biotechnol Bioeng 2021; 118:2448-2459. [PMID: 33719068 DOI: 10.1002/bit.27753] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 02/26/2021] [Accepted: 03/12/2021] [Indexed: 12/27/2022]
Abstract
Clostridium butyricum has been widely used as a probiotic for humans and food animals. However, the mechanisms of beneficial effects of C. butyricum on the host remain poorly understood, largely due to the lack of high-throughput genome engineering tools. Here, we report the exploitation of heterologous Type II CRISPR-Cas9 system and endogenous Type I-B CRISPR-Cas system in probiotic C. butyricum for seamless genome engineering. Although successful genome editing was achieved in C. butyricum when CRISPR-Cas9 system was employed, the expression of toxic cas9 gene result in really poor transformation, spurring us to develop an easy-applicable and high-efficient genome editing tool. Therefore, the endogenous Type I-B CRISPR-Cas machinery located on the megaplasmid of C. butyricum was co-opted for genome editing. In vivo plasmid interference assays identified that ACA and TAA were functional protospacer adjacent motif sequences needed for site-specific CRISPR attacking. Using the customized endogenous CRISPR-Cas system, we successfully deleted spo0A and aldh genes in C. butyricum, yielding an efficiency of up to 100%. Moreover, the conjugation efficiency of endogenous CRISPR-Cas system was dramatically enhanced due to the precluding expression of cas9. Altogether, the two approaches developed herein remarkably expand the existing genetic toolbox available for investigation of C. butyricum.
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Affiliation(s)
- Xiuqing Zhou
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaolu Wang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Huiying Luo
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yaru Wang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yuan Wang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Tao Tu
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xing Qin
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaoyun Su
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yingguo Bai
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Bin Yao
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Huoqing Huang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jie Zhang
- State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
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Wilding-Steele T, Ramette Q, Jacottin P, Soucaille P. Improved CRISPR/Cas9 Tools for the Rapid Metabolic Engineering of Clostridium acetobutylicum. Int J Mol Sci 2021; 22:ijms22073704. [PMID: 33918190 PMCID: PMC8037352 DOI: 10.3390/ijms22073704] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/24/2021] [Accepted: 03/31/2021] [Indexed: 11/16/2022] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas (CRISPR-associated proteins)9 tools have revolutionized biology-several highly efficient tools have been constructed that have resulted in the ability to quickly engineer model bacteria, for example, Escherichia coli. However, the use of CRISPR/Cas9 tools has lagged behind in non-model bacteria, hampering engineering efforts. Here, we developed improved CRISPR/Cas9 tools to enable efficient rapid metabolic engineering of the industrially relevant bacterium Clostridium acetobutylicum. Previous efforts to implement a CRISPR/Cas9 system in C. acetobutylicum have been hampered by the lack of tightly controlled inducible systems along with large plasmids resulting in low transformation efficiencies. We successfully integrated the cas9 gene from Streptococcuspyogenes into the genome under control of the xylose inducible system from Clostridium difficile, which we then showed resulted in a tightly controlled system. We then optimized the length of the editing cassette, resulting in a small editing plasmid, which also contained the upp gene in order to rapidly lose the plasmid using the upp/5-fluorouracil counter-selection system. We used this system to perform individual and sequential deletions of ldhA and the ptb-buk operon.
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Affiliation(s)
- Tom Wilding-Steele
- INP, TBI, INSA, UPS, Université de Toulouse, 31400 Toulouse, France; wilding-@insa-toulouse.fr (T.W.-S.); (Q.R.); (P.J.)
- Institut National de la Recherche Agronomique (INRA), UMR 792, 31077 Toulouse, France
- Centre National de la Recherche Scientifique (CNRS), UMR 5504, 31400 Toulouse, France
| | - Quentin Ramette
- INP, TBI, INSA, UPS, Université de Toulouse, 31400 Toulouse, France; wilding-@insa-toulouse.fr (T.W.-S.); (Q.R.); (P.J.)
- Institut National de la Recherche Agronomique (INRA), UMR 792, 31077 Toulouse, France
- Centre National de la Recherche Scientifique (CNRS), UMR 5504, 31400 Toulouse, France
| | - Paul Jacottin
- INP, TBI, INSA, UPS, Université de Toulouse, 31400 Toulouse, France; wilding-@insa-toulouse.fr (T.W.-S.); (Q.R.); (P.J.)
- Institut National de la Recherche Agronomique (INRA), UMR 792, 31077 Toulouse, France
- Centre National de la Recherche Scientifique (CNRS), UMR 5504, 31400 Toulouse, France
| | - Philippe Soucaille
- INP, TBI, INSA, UPS, Université de Toulouse, 31400 Toulouse, France; wilding-@insa-toulouse.fr (T.W.-S.); (Q.R.); (P.J.)
- Institut National de la Recherche Agronomique (INRA), UMR 792, 31077 Toulouse, France
- Centre National de la Recherche Scientifique (CNRS), UMR 5504, 31400 Toulouse, France
- BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
- Correspondence:
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Hand TH, Roth MO, Smith CL, Shiel E, Klein KN, Gilbert DM, Li H. Catalytically Enhanced Cas9 through Directed Protein Evolution. CRISPR J 2021; 4:223-232. [PMID: 33876948 PMCID: PMC8182482 DOI: 10.1089/crispr.2020.0092] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Guided by the extensive knowledge of CRISPR-Cas9 molecular mechanisms, protein engineering can be an effective method in improving CRISPR-Cas9 toward desired traits different from those of their natural forms. Here, we describe a directed protein evolution method that enables selection of catalytically enhanced CRISPR-Cas9 variants (CECas9) by targeting a shortened protospacer within a toxic gene. We demonstrate the effectiveness of this method with a previously characterized Type II-C Cas9 from Acidothermus cellulolyticus (AceCas9) and show by enzyme kinetics an up to fourfold improvement of the in vitro catalytic efficiency by AceCECas9. We further evolved the more widely used Streptococcus pyogenes Cas9 (SpyCas9) and demonstrated a noticeable improvement in the SpyCECas9-facilitated homology directed repair-based gene insertion in human colon cancer cells.
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Affiliation(s)
- Travis H. Hand
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, USA; Florida State University, Tallahassee, Florida, USA
| | - Mitchell O. Roth
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, USA; Florida State University, Tallahassee, Florida, USA
| | - Chardasia L. Smith
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, USA; and Florida State University, Tallahassee, Florida, USA
| | - Emily Shiel
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, USA; and Florida State University, Tallahassee, Florida, USA
| | - Kyle N. Klein
- Department of Biological Sciences, Florida State University, Tallahassee, Florida, USA
| | - David M. Gilbert
- Department of Biological Sciences, Florida State University, Tallahassee, Florida, USA
| | - Hong Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, USA; Florida State University, Tallahassee, Florida, USA
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, USA; and Florida State University, Tallahassee, Florida, USA
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Mohanraju P, Mougiakos I, Albers J, Mabuchi M, Fuchs RT, Curcuru JL, van Kranenburg R, Robb GB, van der Oost J. Development of a Cas12a-Based Genome Editing Tool for Moderate Thermophiles. CRISPR J 2021; 4:82-91. [PMID: 33538626 DOI: 10.1089/crispr.2020.0086] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The ability of CRISPR-Cas12a nucleases to function reliably in a wide range of species has been key to their rapid adoption as genome engineering tools. However, so far, Cas12a nucleases have been limited for use in organisms with growth temperatures up to 37 °C. Here, we biochemically characterize three Cas12a orthologs for their temperature stability and activity. We demonstrate that Francisella novicida Cas12a (FnCas12a) has great biochemical potential for applications that require enhanced stability, including use at temperatures >37°C. Furthermore, by employing the moderate thermophilic bacterium Bacillus smithii as our experimental platform, we demonstrate that FnCas12a is active in vivo at temperatures up to 43°C. Subsequently, we develop a single-plasmid FnCas12a-based genome editing tool for B. smithii, combining the FnCas12a targeting system with plasmid-borne homologous recombination (HR) templates that carry the desired modifications. Culturing of B. smithii cells at 45°C allows for the uninhibited realization of the HR-based editing step, while a subsequent culturing step at reduced temperatures induces the efficient counterselection of the non-edited cells by FnCas12a. The developed gene-editing tool yields gene-knockout mutants within 3 days, and does not require tightly controllable expression of FnCas12a to achieve high editing efficiencies, indicating its potential for other (thermophilic) bacteria and archaea, including those with minimal genetic toolboxes. Altogether, our findings provide new biochemical insights into three widely used Cas12a nucleases, and establish the first Cas12a-based bacterial genome editing tools for moderate thermophilic microorganisms.
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Affiliation(s)
- Prarthana Mohanraju
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Ioannis Mougiakos
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Justin Albers
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | | | - Ryan T Fuchs
- New England Biolabs, Ipswich, Massachusetts, USA
| | | | - Richard van Kranenburg
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands.,Corbion, Gorinchem, The Netherlands
| | - G Brett Robb
- New England Biolabs, Ipswich, Massachusetts, USA
| | - John van der Oost
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
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Riley LA, Guss AM. Approaches to genetic tool development for rapid domestication of non-model microorganisms. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:30. [PMID: 33494801 PMCID: PMC7830746 DOI: 10.1186/s13068-020-01872-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 12/30/2020] [Indexed: 05/04/2023]
Abstract
Non-model microorganisms often possess complex phenotypes that could be important for the future of biofuel and chemical production. They have received significant interest the last several years, but advancement is still slow due to the lack of a robust genetic toolbox in most organisms. Typically, "domestication" of a new non-model microorganism has been done on an ad hoc basis, and historically, it can take years to develop transformation and basic genetic tools. Here, we review the barriers and solutions to rapid development of genetic transformation tools in new hosts, with a major focus on Restriction-Modification systems, which are a well-known and significant barrier to efficient transformation. We further explore the tools and approaches used for efficient gene deletion, DNA insertion, and heterologous gene expression. Finally, more advanced and high-throughput tools are now being developed in diverse non-model microbes, paving the way for rapid and multiplexed genome engineering for biotechnology.
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Affiliation(s)
- Lauren A Riley
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA
| | - Adam M Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
- Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA.
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Genome Editing of the Anaerobic Thermophile Thermoanaerobacter ethanolicus Using Thermostable Cas9. Appl Environ Microbiol 2020; 87:AEM.01773-20. [PMID: 33067194 DOI: 10.1128/aem.01773-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/04/2020] [Indexed: 12/11/2022] Open
Abstract
Thermoanaerobacter ethanolicus can produce acetate, lactate, hydrogen, and ethanol from sugars resulting from plant carbohydrate polymer degradation at temperatures above 65°C. T. ethanolicus is a promising candidate for thermophilic ethanol fermentations due to the utilization of both pentose and hexose. Although an ethanol balance model in T. ethanolicus has been developed, only a few physiological or biochemical experiments regarding the function of important enzymes in ethanol formation have been carried out. To address this issue, we developed a thermostable Cas9-based system for genome editing of T. ethanolicus As a proof of principle, three genes, including the thymidine kinase gene (tdk), acetaldehyde-alcohol dehydrogenase gene (adhE), and redox sensing protein gene (rsp), were chosen as editing targets, and these genes were edited successfully. As a genetic tool, we tested the gene knockout and a small DNA fragment knock-in. After optimization of the transformation strategies, 77% genome-editing efficiency was observed. Furthermore, our in vivo results revealed that redox sensing protein (RSP) plays a more important role in regulation of energy metabolism, including hydrogen production and ethanol formation. The genetic system provides us with an effective strategy to identify genes involved in biosynthesis and energy metabolism.IMPORTANCE Interest in thermophilic microorganisms as emerging metabolic engineering platforms to produce biofuels and chemicals has surged. Thermophilic microbes for biofuels have attracted great attention, due to their tolerance of high temperature and wide range of substrate utilization. On the basis of the biochemical experiments of previous investigation, the formation of ethanol was controlled via transcriptional regulation and influenced by the relevant properties of specific enzymes in T. ethanolicus Thus, there is an urgent need to understand the physiological function of these key enzymes, which requires genetic manipulations such as deletion or overexpression of genes encoding putative key enzymes. Here, we developed a thermostable Cas9-based engineering tool for gene editing in T. ethanolicus The thermostable Cas9-based genome-editing tool may further be applied to metabolically engineer T. ethanolicus to produce biofuels. This genetic system represents an important expansion of the genetic tool box of anaerobic thermophile T. ethanolicus strains.
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41
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Das A, Hand TH, Smith CL, Wickline E, Zawrotny M, Li H. The molecular basis for recognition of 5'-NNNCC-3' PAM and its methylation state by Acidothermus cellulolyticus Cas9. Nat Commun 2020; 11:6346. [PMID: 33311465 PMCID: PMC7733487 DOI: 10.1038/s41467-020-20204-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/18/2020] [Indexed: 12/13/2022] Open
Abstract
Acidothermus cellulolyticus CRISPR-Cas9 (AceCas9) is a thermophilic Type II-C enzyme that has potential genome editing applications in extreme environments. It cleaves DNA with a 5'-NNNCC-3' Protospacer Adjacent Motif (PAM) and is sensitive to its methylation status. To understand the molecular basis for the high specificity of AceCas9 for its PAM, we determined two crystal structures of AceCas9 lacking its HNH domain (AceCas9-ΔHNH) bound with a single guide RNA and DNA substrates, one with the correct and the other with an incorrect PAM. Three residues, Glu1044, Arg1088, Arg1091, form an intricate hydrogen bond network with the first cytosine and the two opposing guanine nucleotides to confer specificity. Methylation of the first but not the second cytosine base abolishes AceCas9 activity, consistent with the observed PAM recognition pattern. The high sensitivity of AceCas9 to the modified cytosine makes it a potential device for detecting epigenomic changes in genomes.
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Affiliation(s)
- Anuska Das
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA
| | - Travis H Hand
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA
| | - Chardasia L Smith
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA
| | - Ethan Wickline
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA
| | - Michael Zawrotny
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA
| | - Hong Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306, USA.
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA.
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43
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Biorefinery: The Production of Isobutanol from Biomass Feedstocks. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10228222] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Environmental issues have prompted the vigorous development of biorefineries that use agricultural waste and other biomass feedstock as raw materials. However, most current biorefinery products are cellulosic ethanol. There is an urgent need for biorefineries to expand into new bioproducts. Isobutanol is an important bulk chemical with properties that are close to gasoline, making it a very promising biofuel. The use of microorganisms to produce isobutanol has been extensively studied, but there is still a considerable gap to achieving the industrial production of isobutanol from biomass. This review summarizes current metabolic engineering strategies that have been applied to biomass isobutanol production and recent advances in the production of isobutanol from different biomass feedstocks.
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Fenster JA, Eckert CA. High-Throughput Functional Genomics for Energy Production. Curr Opin Biotechnol 2020; 67:7-14. [PMID: 33152605 DOI: 10.1016/j.copbio.2020.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 09/14/2020] [Accepted: 09/21/2020] [Indexed: 10/23/2022]
Abstract
Functional genomics remains a foundational field for establishing genotype-phenotype relationships that enable strain engineering. High-throughput (HTP) methods accelerate the Design-Build-Test-Learn cycle that currently drives synthetic biology towards a forward engineering future. Trackable mutagenesis techniques including transposon insertion sequencing and CRISPR-Cas-mediated genome editing allow for rapid fitness profiling of a collection, or library, of mutants to discover beneficial mutations. Due to the relative speed of these experiments compared to adaptive evolution experiments, iterative rounds of mutagenesis can be implemented for next-generation metabolic engineering efforts to design complex production and tolerance phenotypes. Additionally, the expansion of these mutagenesis techniques to novel bacteria are opening up industrial microbes that show promise for establishing a bio-based economy.
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Affiliation(s)
- Jacob A Fenster
- Chemical and Biological Engineering, University of Colorado, Boulder CO, United States; Renewable and Sustainable Energy Institute, University of Colorado, Boulder CO, United States
| | - Carrie A Eckert
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder CO, United States; National Renewable Energy Laboratory, Golden CO, United States.
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45
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Directed Evolution of CRISPR/Cas Systems for Precise Gene Editing. Trends Biotechnol 2020; 39:262-273. [PMID: 32828556 DOI: 10.1016/j.tibtech.2020.07.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/26/2022]
Abstract
CRISPR technology is a universal tool for genome engineering that has revolutionized biotechnology. Recently identified unique CRISPR/Cas systems, as well as re-engineered Cas proteins, have rapidly expanded the functions and applications of CRISPR/Cas systems. The structures of Cas proteins are complex, containing multiple functional domains. These protein domains are evolutionarily conserved polypeptide units that generally show independent structural or functional properties. In this review, we propose using protein domains as a new way to classify protein engineering strategies for these proteins and discuss common ways to engineer key domains to modify the functions of CRISPR/Cas systems.
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46
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Liu R, Liang L, Freed EF, Choudhury A, Eckert CA, Gill RT. Engineering regulatory networks for complex phenotypes in E. coli. Nat Commun 2020; 11:4050. [PMID: 32792485 PMCID: PMC7426931 DOI: 10.1038/s41467-020-17721-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/07/2020] [Indexed: 12/11/2022] Open
Abstract
Regulatory networks describe the hierarchical relationship between transcription factors, associated proteins, and their target genes. Regulatory networks respond to environmental and genetic perturbations by reprogramming cellular metabolism. Here we design, construct, and map a comprehensive regulatory network library containing 110,120 specific mutations in 82 regulators expected to perturb metabolism. We screen the library for different targeted phenotypes, and identify mutants that confer strong resistance to various inhibitors, and/or enhanced production of target compounds. These improvements are identified in a single round of selection, showing that the regulatory network library is universally applicable and is convenient and effective for engineering targeted phenotypes. The facile construction and mapping of the regulatory network library provides a path for developing a more detailed understanding of global regulation in E. coli, with potential for adaptation and use in less-understood organisms, expanding toolkits for future strain engineering, synthetic biology, and broader efforts.
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Affiliation(s)
- Rongming Liu
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado, USA
| | - Liya Liang
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado, USA
| | - Emily F Freed
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado, USA
| | - Alaksh Choudhury
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado, USA
| | - Carrie A Eckert
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado, USA
- National Renewable Energy Laboratory (NREL), Golden, Colorado, USA
| | - Ryan T Gill
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado, USA.
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.
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47
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Liang L, Liu R, Freed EF, Eckert CA. Synthetic Biology and Metabolic Engineering Employing Escherichia coli for C2-C6 Bioalcohol Production. Front Bioeng Biotechnol 2020; 8:710. [PMID: 32719784 PMCID: PMC7347752 DOI: 10.3389/fbioe.2020.00710] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/08/2020] [Indexed: 12/18/2022] Open
Abstract
Biofuel production from renewable and sustainable resources is playing an increasingly important role within the fuel industry. Among biofuels, bioethanol has been most widely used as an additive for gasoline. Higher alcohols can be blended at a higher volume compared to ethanol and generate lower greenhouse gas (GHG) emissions without a need to change current fuel infrastructures. Thus, these fuels have the potential to replace fossil fuels in support of more environmentally friendly processes. This review summarizes the efforts to enhance bioalcohol production in engineered Escherichia coli over the last 5 years and analyzes the current challenges for increasing productivities for industrial applications.
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Affiliation(s)
- Liya Liang
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO, United States
| | - Rongming Liu
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO, United States
| | - Emily F. Freed
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO, United States
| | - Carrie A. Eckert
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO, United States
- National Renewable Energy Laboratory, Golden, CO, United States
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48
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Xu Z, Li Y, Li M, Xiang H, Yan A. Harnessing the type I CRISPR-Cas systems for genome editing in prokaryotes. Environ Microbiol 2020; 23:542-558. [PMID: 32510745 DOI: 10.1111/1462-2920.15116] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 05/31/2020] [Accepted: 06/02/2020] [Indexed: 12/26/2022]
Abstract
Genetic analysis is crucial to the understanding, exploitation, and control of microorganisms. The advent of CRISPR-Cas-based genome-editing techniques, particularly those mediated by the single-effector (Cas9 and Cas12a) class 2 CRISPR-Cas systems, has revolutionized the genetics in model eukaryotic organisms. However, their applications in prokaryotes are rather limited, largely owing to the exceptional diversity of DNA homeostasis in microorganisms and severe cytotoxicity of overexpressing these nuclease proteins in certain genotypes. Remarkably, CRISPR-Cas systems belonging to different classes and types are continuously identified in prokaryotic genomes and serve as a deep reservoir for expansion of the CRISPR-based genetic toolkits. ~90% of the CRISPR-Cas systems identified so far belong to the class 1 system which hinges on multi-protein effector complexes for DNA interference. Harnessing these widespread native CRISPR-Cas systems for 'built-in' genome editing represents an emerging and powerful genetic tool in prokaryotes, especially in the genetically recalcitrant non-model species and strains. In this progress review, we introduce the general workflow of this emerging editing platform and summarize its establishment in a growing number of prokaryotes by harnessing the most widespread, diverse type I CRISPR-Cas systems present in their genomes. We also discuss the various factors affecting the success and efficiency of this editing platform and the corresponding solutions.
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Affiliation(s)
- Zeling Xu
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Yanran Li
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Ming Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Aixin Yan
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
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49
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Xu Z, Li Y, Yan A. Repurposing the Native Type I-F CRISPR-Cas System in Pseudomonas aeruginosa for Genome Editing. STAR Protoc 2020; 1:100039. [PMID: 33111087 PMCID: PMC7580218 DOI: 10.1016/j.xpro.2020.100039] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Repurposing the broadly distributed native CRISPR-Cas systems in prokaryotes for genome editing is emerging as a new strategy for genetic manipulations. We recently reported the establishment of a single plasmid-mediated, one-step genome-editing technique in a multidrug-resistant genotype of the opportunistic pathogen Pseudomonas aeruginosa by harnessing its endogenous type I-F CRISPR-Cas system. The platform is readily applicable in additional type I-F CRISPR-containing clinical and environmental P. aeruginosa isolates. Herein, we provide the detailed protocol for the methodology. For complete details on the establishment and exploitation of this protocol, please refer to Xu et al. (2019). Workflow to repurpose the native I-F CRISPR-Cas system for genome editing in PA154197 Procedures to characterize native CRISPR-Cas systems in the strains of interest Potential solutions for troubleshooting and expanding the method to other strains
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Affiliation(s)
- Zeling Xu
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Yanran Li
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Aixin Yan
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
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Comprehensive Mining and Characterization of CRISPR-Cas Systems in Bifidobacterium. Microorganisms 2020; 8:microorganisms8050720. [PMID: 32408568 PMCID: PMC7284854 DOI: 10.3390/microorganisms8050720] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/01/2020] [Accepted: 05/08/2020] [Indexed: 12/12/2022] Open
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas (CRISPR-associated cas) systems constitute the adaptive immune system in prokaryotes, which provides resistance against bacteriophages and invasive genetic elements. The landscape of applications in bacteria and eukaryotes relies on a few Cas effector proteins that have been characterized in detail. However, there is a lack of comprehensive studies on naturally occurring CRISPR-Cas systems in beneficial bacteria, such as human gut commensal Bifidobacterium species. In this study, we mined 954 publicly available Bifidobacterium genomes and identified CRIPSR-Cas systems in 57% of these strains. A total of five CRISPR-Cas subtypes were identified as follows: Type I-E, I-C, I-G, II-A, and II-C. Among the subtypes, Type I-C was the most abundant (23%). We further characterized the CRISPR RNA (crRNA), tracrRNA, and PAM sequences to provide a molecular basis for the development of new genome editing tools for a variety of applications. Moreover, we investigated the evolutionary history of certain Bifidobacterium strains through visualization of acquired spacer sequences and demonstrated how these hypervariable CRISPR regions can be used as genotyping markers. This extensive characterization will enable the repurposing of endogenous CRISPR-Cas systems in Bifidobacteria for genome engineering, transcriptional regulation, genotyping, and screening of rare variants.
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